Cut the beans into lengths measuring 3-6
inches (7.5-15 cm). In a wok or large sauté pan over high heat,
heat 1 tablespoon of the canola oil until very hot. Add the
beans and stir-fry until they begin to char and blister, 7-10 minutes.
Transfer the beans to a bowl. Set the pan aside without rinsing.
To make the sauce, in a bowl, stir together the broth, vinegar, soy
sauce, tomato paste, chili sauce, cornstarch and sugar. Return
the pan to high heat, add the remaining 1 tablespoon oil, and heat
until very hot. Add the garlic, celery, green scallions and
ginger and stir-fry until very fragrant, about 2 minutes. Stir
in the pork, chili and preserved vegetable and continue to stir-fry
until the pork is opaque, 2-3 minutes. Return the beans to the
pan and stir-fry for 2 minutes to heat through. Pour the sauce
over the beans and stir-fry until the sauce reduces and thickens, 3-4
minutes. Transfer to a warmed bowl and serve at once.

Note: The term
Sichuan preserved vegetable refers to radishes, mustard greens, napa
cabbage, or turnips that have been pickled in vinegar, salt, chili
paste and Sichuan peppercorns. The pickled vegetables have a
salty taste and crunchy texture. They are sold wrapped in
plastic or in cans or earthenware jugs. Rinse before use to
remove excess brine.